The purpose of this project is to increase and extend the applicability of circular dichroism (CD) and other optical properties to the study of macromolecular structure. In the coming year, we will concentrate on the following lines of research: (1) heme proteins, (2) polypeptide CD, (3) aromatic side-chain contributions to CD, and (4) enzyme-dye interactions and (5) metal-nucleotide interactions. The experimental studies of the CD of hemoglobin at various stages of oxygenation, using the widest possible wavelength range will be pursued. Further calculations will be undertaken to examine the effect of ligand binding on other transitions than the Soret, including the near UV aromatic transitions. The DeVoe theory will also be applied to an analysis of heme-heme interactions as a function of distance and mutual orientation. The DeVoe theory will be extended to include static mixing of transitions (the one-electron effect) and this will be applied to calculations on regular polypeptide structures such as the alpha-helix, poly-L-proline II, beta-structures and beta-turns. CD calculations will also be performed on twisted beta-sheets like those found in proteins, and the interaction of adjacent secondary structural elements (e.g., 2 paralled alpha-helix in proximity to a beta-pleated sheet) will be considered. Aromatic side-chain contributions to protein CD will be studied using fluorescence-detected circular dichroism, which may permit us to ascertain how large such contributions are in the far ultraviolet. The interaction of NADH and such fluorescent analogues as -NAD ion and 1,8-anilino-naphthalene sulfonate with dehydrogenases will also be studied by fluorescence - detected circular dichroism. Our studies of metal-nucleotide interactions by CD will be pursued, focusing on the transition metal ions.